What is the meaning of the letter “g” or “a” after pressure measuring units?
These letters indicate either the “manometric/ instrumental measuring mode” or the “absolute measuring mode”, where the gauge-mode pressure (g from the English gauge) is one measured normally by observing the surrounding pressure and the absolute-mode pressure (a from the Engl. absolute) is measured by observing the zero pressure.
In spite of their inscription on many instruments, abbreviations like barg, psig, kPaA, kPaG, bara, psia, etc. are not legitimate and create conflicts with the international standards – they should not be used.
In order not to engage in details it is essential that you know the following:
Absolute pressure (…a) = manometric pressure (…g) + atmospheric pressure.
We remind you briefly a conversion relationship between pressure measuring units:
1 bar = 100 000 N/m2 = 1.01972 x 10000 kgf/m2 = 1.01972 at (kgf/cm2) = 0.98692 atm = 750.06 torr (mm Hg)
We offer you variants of digital thermo-hygrometers for monitoring the temperature and humidity conditions inside and outside.
Depending on the Maximum/ Minimum, sensor for out-door with 3 m cable, range from -50 to 70 degrees Celsius, 0 to 100 % RH, magnetic clip for on-wall mounting, code 681067938. Contact us!
In order to extract liquids from canisters, barrels it is helpful to use hand pumps with either bulb or piston, made from various materials depending on the corrosiveness of the liquid; we can tell you that a hand pump OTAL (Germany) with bulb, for an immersion depth of 90 cm, at a capacity of 26 l/ min costs approximately 160 euro.
Why is DURAN glass so special?
DURAN® is the world-wide standard for borosilicate glass 3.3 (DIN/ISO 3585).
Its characteristics include maximum chemical resistance and high thermal resistance.
The quality of the laboratory glassware of this trademark is given by the material (in other words by the glass and the glass type) but also by the way the glass is processed during the production process. This affects the characteristics of each glass piece. Having a uniform wall thickness on the entire piece (ex. an Erlenmeyer flask) the improvement of the physical stability and, above all, the thermal shock resistance are ensured. The maximum work temperature with DURAN® is of 500 degrees C.
Starting with January 2004 all laboratory glassware SCHOTT DURAN® is imprinted with an 8-digit batch number proving the traceability of that reference from the producer to the user. With this number (Retrace Code) and with the SCHOTT product use, any user can quickly obtain on the internet a quality certificate per batch (www.schott-duran.com).
Even though the decree 466/79 regarding adhesive the regime of the toxic substances has been abrogated, it is useful to label the place where you keep such substances with warning labels for toxic and very toxic. In this respect we propose you self-adhesive labels with skull, explosion hazard, inflammable etc. Sizes:
– 18×26 mm (one sheet with 30 pieces);
– 26×37 mm (sheet with 12 pieces).
We recommend you the fire blanket for laboratories; the asbestos fabrics are not fashionable anymore, asbestos is avoided due to health reasons; the blankets offered by us are made of glass fibre, are especially thermally insulated, nice at skin contact and non-toxic. They have two places in which they can be grabbed and quickly unfolded when needed. Dimensions 1600×2000 mm, compliant with EN 1869.
NutriDisks are alternatives to the traditional Agar plates. The selective determinations and counting of the colonies are performed more easily with these NutriDisks.
A cellulose disk is impregnated with a dehydrated base nutrient which, after being humidified with sterile distilled water becomes a proper nutritive medium for a micro-organism to be analysed.
NutriDisks are delivered without membrane giving you the possibility of choosing the membranes you consider appropriate.
NutriDisks are available in a wide range of nutrient solutions, for a wide application range, which cover all ranges of microbiological analysis. They are sterile, ready-to-use and valid (at room temperature) for one year; they are packed in Petri box, 10 x 10 pieces.
Example: Standard TTC-NutriDisk, code 10434164 (filtering membrane recommended by ME 25/41, green, gridded, 0.45 microns), for colonies in water, with triphenil tetrazolium chloride. Incubation conditions 48-72 hours at 20 degrees or 48 hours at 30 degrees.
About aerometers and densimeters with or without built-in thermometer:
– the ones from inland have the classic range from 0,07 to 0,07 units. Example: for diesel fuel you need a densimeter or thermo-densimeter from 0,790 to 0,860 g/ml;
– the ones from Germany have other ranges such as: 0,600 to 0,660 / 0,650 to 0,710 / 0,700 to 0,760 etc. or 1,000 to 1,020 / 1,020 to 1,040 etc. depending on the required precision and dimensions.
Note that the calibration in metrology is compulsory only when used in domains which can impair the health of humans (the notion of metrological verification is actually the user’s choice).
You can check the freezing temperature of an antifreeze agent based on mono ethylene glycol more easily determining the index of refraction.
Example: a mix of 50% MEG with 50% water has an index of refraction of 1,383 at 20 degrees C corresponding to -27 degrees freezing point.